Pipe coupling



FIG. 1 is a perspective view of our design for a pipe coupling;

FIG. 2 is an end view of the pipe coupling shown in FIG. 1, the opposite end view being identical thereto;

FIG. 3 is a side view of the pipe coupling shown in FIG. 1, the opposite side view being identical thereto;

FIG. 4 is a top view of the pipe coupling shown in FIG. 1; and,

FIG. 5 is a bottom view of the pipe coupling shown in FIG. 1. 

We claim the ornamental design for a pipe coupling, as shown and described. 